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1 /*
2  * Copyright (C) 2011 The Android Open Source Project
3  *
4  * Licensed under the Apache License, Version 2.0 (the "License");
5  * you may not use this file except in compliance with the License.
6  * You may obtain a copy of the License at
7  *
8  *      http://www.apache.org/licenses/LICENSE-2.0
9  *
10  * Unless required by applicable law or agreed to in writing, software
11  * distributed under the License is distributed on an "AS IS" BASIS,
12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13  * See the License for the specific language governing permissions and
14  * limitations under the License.
15  */
16 
17 /*!
18  * \file      exynos_mc.c
19  * \brief     source file for libexynosv4l2
20  * \author    Jinsung Yang (jsgood.yang@samsung.com)
21  * \author    Sangwoo Park (sw5771.park@samsung.com)
22  * \date      2012/01/17
23  *
24  * <b>Revision History: </b>
25  * - 2012/01/17: Jinsung Yang (jsgood.yang@samsung.com) \n
26  *   Initial version
27  *
28  */
29 
30 #include <stdio.h>
31 #include <stdarg.h>
32 #include <stdlib.h>
33 #include <fcntl.h>
34 #include <errno.h>
35 #include <ctype.h>
36 #include <string.h>
37 #include <sys/types.h>
38 #include <sys/ioctl.h>
39 #include <sys/stat.h>
40 #include <media.h>
41 #include <linux/kdev_t.h>
42 #include <linux/types.h>
43 
44 #include "exynos_v4l2.h"
45 
46 //#define LOG_NDEBUG 0
47 #define LOG_TAG "libexynosv4l2-mc"
48 #include <utils/Log.h>
49 
__media_entity_type(struct media_entity * entity)50 static inline unsigned int __media_entity_type(struct media_entity *entity)
51 {
52     return entity->info.type & MEDIA_ENT_TYPE_MASK;
53 }
54 
__media_debug_default(void * ptr,...)55 static void __media_debug_default(void *ptr, ...)
56 {
57     va_list argptr;
58     va_start(argptr, ptr);
59     vprintf((const char*)ptr, argptr);
60     va_end(argptr);
61 }
62 
__media_debug_set_handler(struct media_device * media,void (* debug_handler)(void *,...),void * debug_priv)63 static void __media_debug_set_handler(
64                 struct media_device *media,
65                 void (*debug_handler)(void *, ...),
66                 void *debug_priv)
67 {
68     if (debug_handler) {
69         media->debug_handler = debug_handler;
70         media->debug_priv = debug_priv;
71     } else {
72         media->debug_handler = __media_debug_default;
73         media->debug_priv = NULL;
74     }
75 }
76 
__media_entity_add_link(struct media_entity * entity)77 static struct media_link *__media_entity_add_link(struct media_entity *entity)
78 {
79     if (entity->num_links >= entity->max_links) {
80         struct media_link *links = entity->links;
81         unsigned int max_links = entity->max_links * 2;
82         unsigned int i;
83 
84         links = (struct media_link*)realloc(links, max_links * sizeof *links);
85         if (links == NULL)
86             return NULL;
87 
88         for (i = 0; i < entity->num_links; ++i)
89             links[i].twin->twin = &links[i];
90 
91         entity->max_links = max_links;
92         entity->links = links;
93     }
94 
95     return &entity->links[entity->num_links++];
96 }
97 
98 
__media_enum_links(struct media_device * media)99 static int __media_enum_links(struct media_device *media)
100 {
101     ALOGD("%s: start", __func__);
102     __u32 id;
103     int ret = 0;
104 
105     for (id = 1; id <= media->entities_count; id++) {
106         struct media_entity *entity = &media->entities[id - 1];
107         struct media_links_enum links;
108         unsigned int i;
109 
110         links.entity = entity->info.id;
111         links.pads = (struct media_pad_desc*)malloc(entity->info.pads * sizeof(struct media_pad_desc));
112         links.links = (struct media_link_desc*)malloc(entity->info.links * sizeof(struct media_link_desc));
113 
114         if (ioctl(media->fd, MEDIA_IOC_ENUM_LINKS, &links) < 0) {
115             ALOGE("Unable to enumerate pads and links (%s)", strerror(errno));
116             free(links.pads);
117             free(links.links);
118             return -errno;
119         }
120 
121         for (i = 0; i < entity->info.pads; ++i) {
122             entity->pads[i].entity = entity;
123             entity->pads[i].index = links.pads[i].index;
124             entity->pads[i].flags = links.pads[i].flags;
125         }
126 
127         for (i = 0; i < entity->info.links; ++i) {
128             struct media_link_desc *link = &links.links[i];
129             struct media_link *fwdlink;
130             struct media_link *backlink;
131             struct media_entity *source;
132             struct media_entity *sink;
133 
134             source = exynos_media_get_entity_by_id(media, link->source.entity);
135             sink = exynos_media_get_entity_by_id(media, link->sink.entity);
136             if (source == NULL || sink == NULL) {
137                 ALOGE("WARNING entity %u link %u from %u/%u to %u/%u is invalid!",
138                       id, i, link->source.entity,
139                       link->source.index,
140                       link->sink.entity,
141                       link->sink.index);
142                 ret = -EINVAL;
143             } else {
144                 fwdlink = __media_entity_add_link(source);
145                 fwdlink->source = &source->pads[link->source.index];
146                 fwdlink->sink = &sink->pads[link->sink.index];
147                 fwdlink->flags = link->flags;
148 
149                 backlink = __media_entity_add_link(sink);
150                 backlink->source = &source->pads[link->source.index];
151                 backlink->sink = &sink->pads[link->sink.index];
152                 backlink->flags = link->flags;
153 
154                 fwdlink->twin = backlink;
155                 backlink->twin = fwdlink;
156             }
157         }
158 
159         free(links.pads);
160         free(links.links);
161     }
162     return ret;
163 }
164 
__media_get_devname_sysfs(struct media_entity * entity)165 static int __media_get_devname_sysfs(struct media_entity *entity)
166 {
167     //struct stat devstat;
168     char devname[32];
169     char sysname[32];
170     char target[1024];
171     char *p;
172     int ret;
173 
174     sprintf(sysname, "/sys/dev/char/%u:%u", entity->info.v4l.major,
175         entity->info.v4l.minor);
176 
177     ret = readlink(sysname, target, sizeof(target));
178     if (ret < 0)
179         return -errno;
180 
181     target[ret] = '\0';
182     p = strrchr(target, '/');
183     if (p == NULL)
184         return -EINVAL;
185 
186     sprintf(devname, "/tmp/%s", p + 1);
187 
188     ret = mknod(devname, 0666 | S_IFCHR, MKDEV(81, entity->info.v4l.minor));
189     strcpy(entity->devname, devname);
190 
191     return 0;
192 }
193 
__media_get_media_fd(const char * filename,struct media_device * media)194 static int __media_get_media_fd(const char *filename, struct media_device *media)
195 {
196     ssize_t num;
197     int media_node;
198     char *ptr;
199     char media_buf[6];
200 
201     ALOGD("%s: %s", __func__, filename);
202 
203     media->fd = open(filename, O_RDWR, 0);
204     if (media->fd < 0) {
205         ALOGE("Open sysfs media device failed, media->fd: %d", media->fd);
206         return -1;
207     }
208 
209     ALOGD("%s: media->fd: %d", __func__, media->fd);
210 
211     return media->fd;
212 
213 }
214 
__media_enum_entities(struct media_device * media)215 static int __media_enum_entities(struct media_device *media)
216 {
217     struct media_entity *entity, *temp_entity;
218     unsigned int size;
219     __u32 id;
220     int ret;
221 
222     temp_entity = entity = (struct media_entity*)calloc(1,  sizeof(struct media_entity));
223     for (id = 0, ret = 0; ; id = entity->info.id) {
224         size = (media->entities_count + 1) * sizeof(*media->entities);
225         media->entities = (struct media_entity*)realloc(media->entities, size);
226 
227         entity = &media->entities[media->entities_count];
228         memset(entity, 0, sizeof(*entity));
229         entity->fd = -1;
230         entity->info.id = id | MEDIA_ENT_ID_FLAG_NEXT;
231         entity->media = media;
232 
233         ret = ioctl(media->fd, MEDIA_IOC_ENUM_ENTITIES, &entity->info);
234 
235         if (ret < 0) {
236             ret = errno != EINVAL ? -errno : 0;
237             break;
238         }
239 
240         /* Number of links (for outbound links) plus number of pads (for
241          * inbound links) is a good safe initial estimate of the total
242          * number of links.
243          */
244         entity->max_links = entity->info.pads + entity->info.links;
245 
246         entity->pads = (struct media_pad*)malloc(entity->info.pads * sizeof(*entity->pads));
247         entity->links = (struct media_link*)malloc(entity->max_links * sizeof(*entity->links));
248         if (entity->pads == NULL || entity->links == NULL) {
249             ret = -ENOMEM;
250             break;
251         }
252 
253         media->entities_count++;
254 
255         /* Find the corresponding device name. */
256         if (__media_entity_type(entity) != MEDIA_ENT_T_DEVNODE &&
257             __media_entity_type(entity) != MEDIA_ENT_T_V4L2_SUBDEV)
258             continue;
259 
260         /* Fall back to get the device name via sysfs */
261         __media_get_devname_sysfs(entity);
262         if (ret < 0)
263             ALOGE("media_get_devname failed");
264     }
265     free(temp_entity);
266 
267     return ret;
268 }
269 
__media_open_debug(const char * filename,void (* debug_handler)(void *,...),void * debug_priv)270 static struct media_device *__media_open_debug(
271         const char *filename,
272         void (*debug_handler)(void *, ...),
273         void *debug_priv)
274 {
275     struct media_device *media;
276     int ret;
277 
278     media = (struct media_device *)calloc(1, sizeof(struct media_device));
279     if (media == NULL) {
280         ALOGE("media: %p", media);
281         return NULL;
282     }
283 
284     __media_debug_set_handler(media, debug_handler, debug_priv);
285 
286     ALOGD("%s: Opening media device %s", __func__, filename);
287     ALOGD("%s: media: %p", __func__, media);
288 
289     media->fd = __media_get_media_fd(filename, media);
290     if (media->fd < 0) {
291         exynos_media_close(media);
292         ALOGE("failed __media_get_media_fd %s", filename);
293         return NULL;
294     }
295 
296     ALOGD("%s: media->fd: %d", __func__, media->fd);
297     ret = __media_enum_entities(media);
298 
299     if (ret < 0) {
300         ALOGE("Unable to enumerate entities for device %s (%s)", filename, strerror(-ret));
301         exynos_media_close(media);
302         return NULL;
303     }
304 
305     ALOGD("%s: Found %u entities", __func__, media->entities_count);
306     ALOGD("%s: Enumerating pads and links", __func__);
307 
308     ret = __media_enum_links(media);
309     if (ret < 0) {
310         ALOGE("Unable to enumerate pads and links for device %s", filename);
311         exynos_media_close(media);
312         return NULL;
313     }
314 
315     return media;
316 }
317 
318 /**
319  * @brief Open a media device.
320  * @param filename - name (including path) of the device node.
321  *
322  * Open the media device referenced by @a filename and enumerate entities, pads and
323  * links.
324  *
325  * @return A pointer to a newly allocated media_device structure instance on
326  * success and NULL on failure. The returned pointer must be freed with
327  * exynos_media_close when the device isn't needed anymore.
328  */
exynos_media_open(const char * filename)329 struct media_device *exynos_media_open(const char *filename)
330 {
331     return __media_open_debug(filename, (void (*)(void *, ...))fprintf, stdout);
332 }
333 
334 /**
335  * @brief Close a media device.
336  * @param media - device instance.
337  *
338  * Close the @a media device instance and free allocated resources. Access to the
339  * device instance is forbidden after this function returns.
340  */
exynos_media_close(struct media_device * media)341 void exynos_media_close(struct media_device *media)
342 {
343     unsigned int i;
344 
345     if (media->fd != -1)
346         close(media->fd);
347 
348     for (i = 0; i < media->entities_count; ++i) {
349         struct media_entity *entity = &media->entities[i];
350 
351         free(entity->pads);
352         free(entity->links);
353         if (entity->fd != -1)
354             close(entity->fd);
355     }
356 
357     free(media->entities);
358     free(media);
359 }
360 
361 /**
362  * @brief Locate the pad at the other end of a link.
363  * @param pad - sink pad at one end of the link.
364  *
365  * Locate the source pad connected to @a pad through an enabled link. As only one
366  * link connected to a sink pad can be enabled at a time, the connected source
367  * pad is guaranteed to be unique.
368  *
369  * @return A pointer to the connected source pad, or NULL if all links connected
370  * to @a pad are disabled. Return NULL also if @a pad is not a sink pad.
371  */
exynos_media_entity_remote_source(struct media_pad * pad)372 struct media_pad *exynos_media_entity_remote_source(struct media_pad *pad)
373 {
374     unsigned int i;
375 
376     if (!(pad->flags & MEDIA_PAD_FL_SINK))
377         return NULL;
378 
379     for (i = 0; i < pad->entity->num_links; ++i) {
380         struct media_link *link = &pad->entity->links[i];
381 
382         if (!(link->flags & MEDIA_LNK_FL_ENABLED))
383             continue;
384 
385         if (link->sink == pad)
386             return link->source;
387     }
388 
389     return NULL;
390 }
391 
392 /**
393  * @brief Find an entity by its name.
394  * @param media - media device.
395  * @param name - entity name.
396  * @param length - size of @a name.
397  *
398  * Search for an entity with a name equal to @a name.
399  *
400  * @return A pointer to the entity if found, or NULL otherwise.
401  */
exynos_media_get_entity_by_name(struct media_device * media,const char * name,size_t length)402 struct media_entity *exynos_media_get_entity_by_name(struct media_device *media,
403                           const char *name, size_t length)
404 {
405     unsigned int i;
406     struct media_entity *entity;
407 
408     for (i = 0; i < media->entities_count; ++i) {
409         entity = &media->entities[i];
410 
411         if (strncmp(entity->info.name, name, length) == 0)
412             return entity;
413     }
414 
415     return NULL;
416 }
417 
418 /**
419  * @brief Find an entity by its ID.
420  * @param media - media device.
421  * @param id - entity ID.
422  *
423  * Search for an entity with an ID equal to @a id.
424  *
425  * @return A pointer to the entity if found, or NULL otherwise.
426  */
exynos_media_get_entity_by_id(struct media_device * media,__u32 id)427 struct media_entity *exynos_media_get_entity_by_id(struct media_device *media,
428                         __u32 id)
429 {
430     unsigned int i;
431 
432     for (i = 0; i < media->entities_count; ++i) {
433         struct media_entity *entity = &media->entities[i];
434 
435         if (entity->info.id == id)
436             return entity;
437     }
438 
439     return NULL;
440 }
441 
442 /**
443  * @brief Configure a link.
444  * @param media - media device.
445  * @param source - source pad at the link origin.
446  * @param sink - sink pad at the link target.
447  * @param flags - configuration flags.
448  *
449  * Locate the link between @a source and @a sink, and configure it by applying
450  * the new @a flags.
451  *
452  * Only the MEDIA_LINK_FLAG_ENABLED flag is writable.
453  *
454  * @return 0 on success, -1 on failure:
455  *       -ENOENT: link not found
456  *       - other error codes returned by MEDIA_IOC_SETUP_LINK
457  */
exynos_media_setup_link(struct media_device * media,struct media_pad * source,struct media_pad * sink,__u32 flags)458 int exynos_media_setup_link(struct media_device *media,
459              struct media_pad *source,
460              struct media_pad *sink,
461              __u32 flags)
462 {
463     struct media_link *link;
464     struct media_link_desc ulink;
465     unsigned int i;
466     int ret;
467 
468     for (i = 0; i < source->entity->num_links; i++) {
469         link = &source->entity->links[i];
470 
471         if (link->source->entity == source->entity &&
472             link->source->index == source->index &&
473             link->sink->entity == sink->entity &&
474             link->sink->index == sink->index)
475             break;
476     }
477 
478     if (i == source->entity->num_links) {
479         ALOGE("Link not found");
480         return -ENOENT;
481     }
482 
483     /* source pad */
484     ulink.source.entity = source->entity->info.id;
485     ulink.source.index = source->index;
486     ulink.source.flags = MEDIA_PAD_FL_SOURCE;
487 
488     /* sink pad */
489     ulink.sink.entity = sink->entity->info.id;
490     ulink.sink.index = sink->index;
491     ulink.sink.flags = MEDIA_PAD_FL_SINK;
492 
493     ulink.flags = flags | (link->flags & MEDIA_LNK_FL_IMMUTABLE);
494 
495     ret = ioctl(media->fd, MEDIA_IOC_SETUP_LINK, &ulink);
496     if (ret == -1) {
497         ALOGE("Unable to setup link (%s)", strerror(errno));
498         return -errno;
499     }
500 
501     link->flags = ulink.flags;
502     link->twin->flags = ulink.flags;
503     return 0;
504 }
505 
506 /**
507  * @brief Reset all links to the disabled state.
508  * @param media - media device.
509  *
510  * Disable all links in the media device. This function is usually used after
511  * opening a media device to reset all links to a known state.
512  *
513  * @return 0 on success, or a negative error code on failure.
514  */
exynos_media_reset_links(struct media_device * media)515 int exynos_media_reset_links(struct media_device *media)
516 {
517     unsigned int i, j;
518     int ret;
519 
520     for (i = 0; i < media->entities_count; ++i) {
521         struct media_entity *entity = &media->entities[i];
522 
523         for (j = 0; j < entity->num_links; j++) {
524             struct media_link *link = &entity->links[j];
525 
526             if (link->flags & MEDIA_LNK_FL_IMMUTABLE ||
527                 link->source->entity != entity)
528                 continue;
529 
530             ret = exynos_media_setup_link(media, link->source, link->sink,
531                            link->flags & ~MEDIA_LNK_FL_ENABLED);
532             if (ret < 0)
533                 return ret;
534         }
535     }
536 
537     return 0;
538 }
539 
540 #ifdef HAVE_LIBUDEV
541 
542 #include <libudev.h>
543 
__media_udev_open(struct udev ** udev)544 static inline int __media_udev_open(struct udev **udev)
545 {
546     *udev = udev_new();
547     if (*udev == NULL)
548         return -ENOMEM;
549     return 0;
550 }
551 
__media_udev_close(struct udev * udev)552 static inline void __media_udev_close(struct udev *udev)
553 {
554     if (udev != NULL)
555         udev_unref(udev);
556 }
557 
__media_get_devname_udev(struct udev * udev,struct media_entity * entity)558 static int __media_get_devname_udev(struct udev *udev,
559         struct media_entity *entity)
560 {
561     struct udev_device *device;
562     dev_t devnum;
563     const char *p;
564     int ret = -ENODEV;
565 
566     if (udev == NULL)
567         return -EINVAL;
568 
569     devnum = makedev(entity->info.v4l.major, entity->info.v4l.minor);
570     ALOGE("looking up device: %u:%u",
571           major(devnum), minor(devnum));
572     device = udev_device_new_from_devnum(udev, 'c', devnum);
573     if (device) {
574         p = udev_device_get_devnode(device);
575         if (p) {
576             strncpy(entity->devname, p, sizeof(entity->devname));
577             entity->devname[sizeof(entity->devname) - 1] = '\0';
578         }
579         ret = 0;
580     }
581 
582     udev_device_unref(device);
583 
584     return ret;
585 }
586 
587 #else    /* HAVE_LIBUDEV */
588 
589 struct udev;
590 
__media_udev_open(struct udev ** udev)591 static inline int __media_udev_open(struct udev **udev) { return 0; }
592 
__media_udev_close(struct udev * udev)593 static inline void __media_udev_close(struct udev *udev) { }
594 
__media_get_devname_udev(struct udev * udev,struct media_entity * entity)595 static inline int __media_get_devname_udev(struct udev *udev,
596         struct media_entity *entity)
597 {
598     return -ENOTSUP;
599 }
600 
601 #endif    /* HAVE_LIBUDEV */
602 
603 /**
604  * @brief Parse string to a pad on the media device.
605  * @param media - media device.
606  * @param p - input string
607  * @param endp - pointer to string where parsing ended
608  *
609  * Parse NULL terminated string describing a pad and return its struct
610  * media_pad instance.
611  *
612  * @return Pointer to struct media_pad on success, NULL on failure.
613  */
exynos_media_parse_pad(struct media_device * media,const char * p,char ** endp)614 struct media_pad *exynos_media_parse_pad(struct media_device *media,
615                   const char *p, char **endp)
616 {
617     unsigned int entity_id, pad;
618     struct media_entity *entity;
619     char *end;
620 
621     for (; isspace(*p); ++p);
622 
623     if (*p == '"') {
624         for (end = (char *)p + 1; *end && *end != '"'; ++end);
625         if (*end != '"')
626             return NULL;
627 
628         entity = exynos_media_get_entity_by_name(media, p + 1, end - p - 1);
629         if (entity == NULL)
630             return NULL;
631 
632         ++end;
633     } else {
634         entity_id = strtoul(p, &end, 10);
635         entity = exynos_media_get_entity_by_id(media, entity_id);
636         if (entity == NULL)
637             return NULL;
638     }
639     for (; isspace(*end); ++end);
640 
641     if (*end != ':')
642         return NULL;
643     for (p = end + 1; isspace(*p); ++p);
644 
645     pad = strtoul(p, &end, 10);
646     for (p = end; isspace(*p); ++p);
647 
648     if (pad >= entity->info.pads)
649         return NULL;
650 
651     for (p = end; isspace(*p); ++p);
652     if (endp)
653         *endp = (char *)p;
654 
655     return &entity->pads[pad];
656 }
657 
658 /**
659  * @brief Parse string to a link on the media device.
660  * @param media - media device.
661  * @param p - input string
662  * @param endp - pointer to p where parsing ended
663  *
664  * Parse NULL terminated string p describing a link and return its struct
665  * media_link instance.
666  *
667  * @return Pointer to struct media_link on success, NULL on failure.
668  */
exynos_media_parse_link(struct media_device * media,const char * p,char ** endp)669 struct media_link *exynos_media_parse_link(
670         struct media_device *media,
671         const char *p,
672         char **endp)
673 {
674     struct media_link *link;
675     struct media_pad *source;
676     struct media_pad *sink;
677     unsigned int i;
678     char *end;
679 
680     source = exynos_media_parse_pad(media, p, &end);
681     if (source == NULL)
682         return NULL;
683 
684     if (end[0] != '-' || end[1] != '>')
685         return NULL;
686     p = end + 2;
687 
688     sink = exynos_media_parse_pad(media, p, &end);
689     if (sink == NULL)
690         return NULL;
691 
692     *endp = end;
693 
694     for (i = 0; i < source->entity->num_links; i++) {
695         link = &source->entity->links[i];
696 
697         if (link->source == source && link->sink == sink)
698             return link;
699     }
700 
701     return NULL;
702 }
703 
704 /**
705  * @brief Parse string to a link on the media device and set it up.
706  * @param media - media device.
707  * @param p - input string
708  *
709  * Parse NULL terminated string p describing a link and its configuration
710  * and configure the link.
711  *
712  * @return 0 on success, or a negative error code on failure.
713  */
exynos_media_parse_setup_link(struct media_device * media,const char * p,char ** endp)714 int exynos_media_parse_setup_link(
715         struct media_device *media,
716         const char *p,
717         char **endp)
718 {
719     struct media_link *link;
720     __u32 flags;
721     char *end;
722 
723     link = exynos_media_parse_link(media, p, &end);
724     if (link == NULL) {
725         ALOGE("Unable to parse link");
726         return -EINVAL;
727     }
728 
729     p = end;
730     if (*p++ != '[') {
731         ALOGE("Unable to parse link flags");
732         return -EINVAL;
733     }
734 
735     flags = strtoul(p, &end, 10);
736     for (p = end; isspace(*p); p++);
737     if (*p++ != ']') {
738         ALOGE("Unable to parse link flags");
739         return -EINVAL;
740     }
741 
742     for (; isspace(*p); p++);
743     *endp = (char *)p;
744 
745     ALOGD("%s: Setting up link %u:%u -> %u:%u [%u]", __func__,
746           link->source->entity->info.id, link->source->index,
747           link->sink->entity->info.id, link->sink->index,
748           flags);
749 
750     return exynos_media_setup_link(media, link->source, link->sink, flags);
751 }
752 
753 /**
754  * @brief Parse string to link(s) on the media device and set it up.
755  * @param media - media device.
756  * @param p - input string
757  *
758  * Parse NULL terminated string p describing link(s) separated by
759  * commas (,) and configure the link(s).
760  *
761  * @return 0 on success, or a negative error code on failure.
762  */
exynos_media_parse_setup_links(struct media_device * media,const char * p)763 int exynos_media_parse_setup_links(struct media_device *media, const char *p)
764 {
765     char *end;
766     int ret;
767 
768     do {
769         ret = exynos_media_parse_setup_link(media, p, &end);
770         if (ret < 0)
771             return ret;
772 
773         p = end + 1;
774     } while (*end == ',');
775 
776     return *end ? -EINVAL : 0;
777 }
778